How Mistletoe Works

Mistletoe (Phoradendron flavescens or Viscum album) is a parasitic plant that grows on trees, particularly hardwood trees like oak and apple. A parasite is a plant or animal that needs another plant or animal to survive. As mistletoe grows on a tree and uses its roots to invade a tree's bark, which allows mistletoe to absorb the tree's nutrients. Sometimes, mistletoe can harm a tree and cause deformities in a tree's branches, but usually it doesn't kill its host. If the host dies, the mistletoe dies.

Mistletoe produces its own food by photosynthesis, and is able to live on its own, although it is mostly found in trees. It's common for a mistletoe plant to grow on top of another mistletoe plant.

Mistletoe is easy to spot in the winter because its leaves stay green all year long. In the United States, it grows in tropical and subtropical regions (from New Jersey to Florida). Mistletoe has pointy, green, leathery leaves, with waxy berries that are either red or white. The plant's flowers can be a wide variety of colors, from bright red to yellow to green.

Ingesting mistletoe can cause severe stomach cramps and diarrhea, and in some cases can be fatal. If you have mistletoe in your house this holiday season, be sure that it is in a place where children and pets won't be able to get to it.

Spreading the Seed

The red-and-white berries that grow on mistletoe are eaten by birds that eventually leave their droppings at their favorite hang-out spot -- on a tree branch. The droppings contain seeds that sprout roots into the tree branch. The birds also help spread the seed by wiping their beaks on the tree bark to clean off the sticky seeds after they've eaten. The seeds are sticky because of the juice inside the berry. This stickiness helps the seeds stay in the tree rather than falling to the ground. Within six weeks, the mistletoe plant begins growing, although it takes five years to flower.

In the next section, we'll look at the history behind mistletoe and find out what ancient Druids used it for.